In order to make use of mobile network resource effectively, MBMS (Multimedia Broadcast Multicast Service) is proposed by the Third Generation Partnership Project (3GPP), that is, a data source is provided in the mobile network for transmitting data to multiple users which is called Point-to-multipoint service, so that the network resource sharing is realized, and the utilization rate of the network resource is improved, especially the precious air interface resources. MBMS can not only realize the message multicast and broadcast of plain text with low speed, but also realize the multicast and broadcast of multimedia service with high speed. Various and plentiful video, audio, and multimedia services can be provided, which undoubtedly conforms to the development trend of the future mobile data and provides a better service prospect for the development of the mobile communication.
FIG. 1 is a structural model drawing of MBMS service system. As shown in FIG. 1, the Broadcast-Multicast Service Center (BM-SC) is a newly added mobile network functional entity, which is the entrance of the content provider, and is used for authorizing and initiating MBMS bearer service in mobile network, and planning for transmitting MBMS content based on the scheduled time.
For the existing WCDMA packet network functional entity: a General Packet Radio Service Gateway Support Node (GGSN), a Serving General Packet Radio Service Support Node (SGSN), a Radio Access Net (RAN) and User Equipment (UE), the MBMS related functions and processes are also needed to be added.
MBMS is divided into Broadcast Service and Multicast Service. The transmitting of MBMS service is limited to a certain range, namely, the transmitting of each MBMS service is restricted to a certain area, and the area is known as the service area corresponding to MBMS service. Based on 3GPP protocol, the transmitting area of the broadcast service is defined as Broadcast service area of the broadcast service, and the transmitting area of the multicast service is defined as Multicast service area. Considering the regional characteristics of some MBMS services, such as weather forecast, road traffic information and so on, the transmitting content is related to the area in which UE is located. When UE is located in a specific area of MBMS SA, only the contents related to the area are needed to be received, through which a requirement that different service contents are transmitted in different areas for the same MBMS service is educed. Therefore, Local Broadcast Area and Local Multicast Area are separately defined for broadcast service and multicast service by 3GPP.
FIG. 2 is a relationship diagram of MBMS SA and local service area of the prior art. As shown in FIG. 2. Each MBMS broadcast service has a broadcast service area, and the broadcast service area includes one or a plurality of local broadcast areas. The service contents related to the local area are only transmitted in local broadcast area, and the transmitting service contents are different in different local broadcast areas. Each MBMS multicast service has a multicast service area, and the multicast service area includes one or a plurality of local multicast areas. The service contents related to the local area are only transmitted in local multicast area, and the transmitting service contents are different in different local multicast areas.
MBMS service date is transmitted via MBMS bearer, and MBMS bearer is managed via MBMS session. One MBMS session is corresponding to one MBMS bearer, and each MBMS session is corresponding to a MBMS Service Area (MBMS SA). MBMS SA is composed of one or a plurality of MBMS Service Area Identity (MBMS SA ID). Each MBMS SA ID is corresponding to one or a plurality of subzones in RNC (Radio Network Controller). When MBMS session begins, MBMS SA is passed through GGSN via BM-SC and transmitted to RNC via SGSN, after RNC receives MBMS session beginning request, MBMS service is only provided in the cell within MBMS SA.
If a MBMS SA is divided into a plurality of local areas, MBMS bearers for bearing service data are required to be different as the service contents transmitted by different areas are different. Therefore, each local area is separately established a MBMS session by BM-SC, namely, a plurality of parallel MBMS sessions is initiated. The parallel MBMS sessions use the same
TMGI (Temporary Mobile Group Identity), which should be marked that the sessions belong to the same MBMS service. As the MBMS service contents transmitted on the same local area are the same, the corresponding MBMS SA is different for the parallel MBMS session of the same MBMS service in the different local area. In other words, the cells included in MBMS SA which is corresponding to the MBMS sessions in different local areas of the same MBMS service can not be overlapped with each other; otherwise, UE may receive service contents from multiple local areas in the overlapped cells.
FIG. 3 is the beginning process flowchart of Iu interface MBMS session of the prior 3GPP. As show in FIG. 3, the following steps are included:
S302, “a MBMS session starts” message is transmitted to the RNC by means of SGSN to request the RNC to notice the start of UE MBMS session on the corresponding MBMS service area, and the MBMS SA is included in the message;
S304, The RNC receives the message “a MBMS session starts” and detects whether there are other sessions established of the same MBMS service in the RNC and the SGSN;
S306, if the overlap of the MBMS SA which is corresponding to other sessions established and the MBMS SA brought by the new message sent by the SGSN exist, the MBMS SA of the message is deemed to be illegal, and return the message “the MBMS session start fails” to the SGSN;
S308, if other sessions established on the same MBMS service exist, or the MBMS SA which is corresponding to other sessions and the MBMS SA brought by the new message sent by the SGSN don't overlap. The message can be processed normally. The message that the MBMS session start to response or the message that the start of the MBMS session is failed will be returned to SGSN according to the processing result.
Wherein, the demand for modifying MBMS SA is also introduced in the R7 edition of 3GPP for MBMS broadcast service, namely, in the process of MBMS session, BM-SC can modify the service area of MBMS broadcast service.
FIG. 4 is an updating process flowchart of Iu interface MBMS session of the 3GPP in the prior art. As shown in FIG. 4, the following steps are included:
S402, “a MBMS session updating” message is transmitted to RNC by means of SGSN to notice that the service area corresponding to MBMS broadcast service is modified, and the modified MBMS SA is included in the message;
S404, The RNC receives the message “a MBMS session updating” and does not detect whether the modified MBMS SA and the MBMS service of other sessions of the same service overlaps with each other, and the MBMS session updating request should be processed normally, namely, the cell included in the unmodified MBMS SA and the modified MBMS SA should be compared;
S406, The MBMS bearer is established in the cell which is not included in the unmodified service area but is included in the modified service area (S406a), the MBMS bearer is deleted in the cell which is included in the unmodified service area but is not included in the modified service area (S406b), and the MBMS bearer will not be affected in the cell which is included both in the unmodified service area and the modified service area (S406c).
In the prior art, under the condition that a MBMS service is corresponding to a plurality of local areas, when RNC receives the MBMS session updating of the parallel session of the same MBMS service, the overlap of the cells with different sessions included in MBMS SA is not detected, which can lead that the same cell under RNC belongs to a plurality of local areas of the same MBMS service after MBMS session is updated. UE under the overlapped cell can receive the same MBMS service and a plurality set of service contents from different areas, which violates the unmodified intention of MBMS service local area defined by 3GPP.
Therefore, an updating method and device for an Iu interface supported parallel Multimedia Broadcast Multicast Service session is urgently desired to solve the problems existed in the protocol of the prior art.